CHEM 305 Chapter 5, 6, and 7 Exam
Naturally occurring iron contains 5.82% 54Fe, 91.66 % 56Fe, 2.19% 57Fe, and 0.33% 58Fe. The respective atomic masses are 53.940 amu, 55.935 amu, 56.935 amu, and 57.933 amu. Calculate the average atomic mass of iron.
55.847 amu
All of the statements are true for spontaneous reactions EXCEPT A). the reaction rate is determined by the value of ΔG. B). if the enthalpy change is unfavorable, they occur at a high temperature. C). the value of ΔG is unaffected by a catalyst. D). they are said to be exergonic. E). the value of ΔG is less than zero.
A). the reaction rate is determined by the value of ΔG.
In the process of dissolving sugar in water, the entropy increases. This means that the sign of ΔS is ________, and that the randomness of the system ________. A). negative; decreases B). undetermined; increases C). positive; increases D). negative; increases E). positive; decreases
C). positive; increases
For the following reaction, increasing the pressure will cause the equilibrium to ________. 2 SO₂ (g) + O₂ (g) ↔ 2 SO₃ (g) + heat A). remain unchanged, but the reaction mixture will get warmer B). remain unchanged, but the reaction mixture will get cooler C). shift to the right, towards products D). shift to the left, towards reactants E). Pressure has no effect on equilibrium.
C). shift to the right, towards products
The position of the equilibrium for a system where K = 4.6 × 10⁻¹⁵ can be described as being favored to ________; the concentration of products is relatively ________. A). the right; large B). the left; large C). the left; small D). the right; small E). neither direction; large
C). the left; small
When the reaction shown is correctly balanced, the coefficients are: ____ HBr + ____ Ca(OH)₂ → ____ CaBr₂ + ____ H₂O A). 2, 1, 1, 1 B). 2, 2, 1, 1 C). 1, 1, 1, 2 D). 2, 1, 1, 2 E). 2, 1, 2, 2
D). 2, 1, 1, 2
A thimble of water contains 4.0 × 10²¹ molecules. The number of moles of H₂O is: A). 2.4 × 10⁴⁵ B). 2.4 × 10⁻²³ C). 6.6 × 10⁻²³ D). 6.6 × 10⁻³ E). 2.4 × 10²³
D). 6.6 × 10⁻³
Consider the reaction shown: N₂ + O₂ → 2 NO ΔH = 43.2 kcal When 50.0 g of N₂ react, ________ kcal will be ________. A). 43.2; produced B). 2160; produced C). 77.1; produced D). 77.1; consumed E). 2160; consumed
D). 77.1; consumed
The number of grams in 0.350 mol of Na is ________. A). 23.0 B). 0.350 C). 11.0 D). 8.05 E). 65.7
D). 8.05
The formula weight of ammonium carbonate, (NH₄)₂CO₃, is ________ amu. A). 180.17 B). 82.10 C). 64.11 D). 96.09 E). 120.13
D). 96.09
For the reaction given below, what quantity of heat will be produced if 90.0 g of C3H8 are consumed in the reaction? C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O + 488 kcal A). 976 kcal B). 488 kcal C). 332 kcal D). 996 kcal E). 239 kcal
D). 996 kcal
The formula for carbon disulfide is ________. A). CaS₂ B). (CS)₂ C). C₂S D). CS₂ E). CSi₂
D). CS₂
Which reaction is an example of an acid-base reaction? A). H₂CO₃ (aq) → H₂O(l) + CO₂ (g) B). FeCl₃ (aq) + 3 KOH(aq) → Fe(OH)₃ (s) + 3 KCl(aq) C). 6 HCl(aq) + 2 Al(s) → 2 AlCl₃ (aq) + 3 H₂ (g) D). H₂SO₄ (aq) + Ca(OH₂2 (aq) → CaSO₄ (aq) + 2H₂O(l) E). 2 Hg(l) + O₂(g) →2 HgO(s)
D). H₂SO₄ (aq) + Ca(OH₂2 (aq) → CaSO₄ (aq) + 2H₂O(l)
Which of the following conditions characterizes a system in a state of chemical equilibrium? A). Concentrations of reactants and products are equal. B). Product concentrations are greater than reactant concentrations. C). Rate of forward reaction has dropped to zero. D). Reactants are being consumed at the same rate they are being produced. E). Reactant molecules no longer react with each other.
D). Reactants are being consumed at the same rate they are being produced.
4 PCl₃ (l) → P₄ (s) + 6 Cl₂ (g) ΔH = 304.0 kcal Based on the reaction shown, which statement is TRUE? A). When 123.88 g P₄ (s) are produced, 304.0 kcal are released. B). When 137.14 g PCl₃ (l) react, 304.0 kcal are consumed. C). When 548.56 g PCl₃ (l) react, 304.0 kcal are released. D). When 1 mol P₄ (s) is produced, 304.0 kcal are consumed. E). When 1 mol PCl₃ (l) reacts, 304.0 kcal are released.
D). When 1 mol P₄ (s) is produced, 304.0 kcal are consumed.
The smallest amount of an element that retains that element's characteristics is the A). molecule. B). neutron. C). electron. D). atom. E). proton.
D). atom.
If heat is consumed during a reaction, the reaction is said to be ________. A). endergonic B). exothermic C). exothermic D). endothermic E). can't tell.
D). endothermic
The concept of free energy allows prediction of spontaneity of a process by considering the changes in ________ and ________ during the process. A). entropy; temperature B). enthalpy; mass C). enthalpy; temperature D). enthalpy; entropy E). entropy; mass
D). enthalpy; entropy
Entropy is used to A). explain how energy is stored. B). explain how an exothermic reaction can become endothermic. C). explain why most chemical reactions are exothermic. D). indicate the disorder of a system. E). none of the above
D). indicate the disorder of a system.
All of the statements regarding the symbol ΔG are true EXCEPT A). it allows us to identify an endergonic reaction. B). it refers to the free energy of the reaction. C). it allows us to predict the spontaneity of a reaction. D). it allows us to identify an exothermic reaction. E). it describes the effect of both enthalpy and entropy on a reaction.
D). it allows us to identify an exothermic reaction.
The following reaction can be classified as what type(s) of reaction(s)? 2 Al(OH)₃ (aq) + 3 H₂SO₄(aq) → Al₂(SO₄)₃ (s) + 6 H₂O (l) A). precipitation B). acid-base neutralization C). redox reaction D). precipitation and acid-base neutralization
D). precipitation and acid-base neutralization
For the following reaction, increasing the pressure will cause the equilibrium to ________. 2 SO₂ (g) + O₂ (g) ↔ 2 SO₃ (g) + heat A). remain unchanged, but the reaction mixture will get warmer B). shift to the left, towards reactants C). remain unchanged, but the reaction mixture will get cooler D). shift to the right, towards products E). Pressure has no effect on equilibrium.
D). shift to the right, towards products
A student weighed 0.550 g of lithium chloride, LiCl, to use in a reaction. How many moles is this? A). 42.39 B). 23.31 C). 77.08 D). 5.11 E). 0.0130
E). 0.0130
How many moles of CO₂ are produced when 2.5 moles of O₂ react according to the following equation? C₃H₅ + 5 O₂ → 3 CO₂ + 4 H₂O A). 6 B). 3 C). 5 D). 18 E). 1.5
E). 1.5
The molar mass of Fe(OH)₃ is ________ g. A). 74.88 B). 104.86 C). 89.87 D). 72.86 E). 106.87
E). 106.87
N₂ + O₂ → 2 NO ΔH = 43.2 kcal Based on the reaction shown, which statement is TRUE? A). 43.2 kcal are consumed when 1.00 g of O₂ reacts. B). 43.2 kcal are consumed when 1.00 g of NO is produced. C). 43.2 kcal are consumed when 1.00 g of N₂ reacts. D). 43.2 kcal are produced when 1.00 mole of NO is produced. E). 43.2 kcal are consumed when 1.00 mole of O₂ reacts.
E). 43.2 kcal are consumed when 1.00 mole of O₂ reacts.
The molar mass of butane, C₄H₁₀, is ________ grams. A). 52.08 B). 68.24 C). 49.05 D). 22.01 E). 58.12
E). 58.12
The combination of ions most likely to produce a precipitate is A). NH₄⁺ and SO₄²⁻. B). Li⁺ and PO₄³⁻. C). Mg²⁺ and C₂H₃O₂⁻. D). Pb²⁺ and NO₃⁻. E). Fe³⁺ and OH⁻.
E). Fe³⁺and OH⁻.
Which of the following conditions characterizes a system in a state of chemical equilibrium? A). Rate of forward reaction has dropped to zero. B). Product concentrations are greater than reactant concentrations. C). Concentrations of reactants and products are equal. D). Reactant molecules no longer react with each other. E). Reactants are being consumed at the same rate they are being produced.
E). Reactants are being consumed at the same rate they are being produced.
For a chemical reaction to occur, all of the following must happen EXCEPT A). chemical bonds in the reactants must break. B). reactant particles must collide with the correct orientation. C). chemical bonds in the products must form. D). reactant particles must collide with enough energy for change to occur. E). a large enough number of collisions must occur.
E). a large enough number of collisions must occur.
A process or reaction which takes in heat from the surroundings is said to be A). conservative. B). endergonic. C). exothermic. D). isothermal. E). endothermic.
E). endothermic.
A process or reaction which releases heat to the surroundings is said to be A). exergonic. B). conservative. C). isothermal. D). endothermic. E). exothermic.
E). exothermic.
Consider the reaction shown: 2 CO (g) + O₂ (g) → CO₂ (g) + 135.2 kcal This reaction is ________ because the sign of ΔH is ________. A). exothermic; neither positive nor negative B). exothermic; positive C). endothermic; negative D). endothermic; positive E). exothermic; negative
E). exothermic; negative
Consider the reaction shown: C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O + 488 kcal We can say that this reaction is ________ and that the sign of ΔH is ________. A). exothermic; positive B). endothermic; negative C). exothermic; neither positive nor negative D). endothermic; positive E). exothermic; negative
E). exothermic; negative
All of the statements regarding the symbol "ΔH" are correct EXCEPT A). it can be called enthalpy change. B). it can be called heat of reaction. C). it represents the difference between the energy used in breaking bonds and the energy released in forming bonds in a chemical reaction. D). it has a negative value for an exothermic reaction. E). it can be called entropy change.
E). it can be called entropy change.
Which of the following causes a chemical change? A). digging a hole B). pumping gasoline C). winding an alarm clock D). slicing a tomato E). metabolizing fat
E). metabolizing fat
2 Al₂O₃ (s) → 4 Al (s) + 3 O₂ (g) ΔG = +138 kcal Consider the contribution of entropy to the spontaneity of this reaction. As written, the reaction is ________, and the entropy of the system ________. A). spontaneous; decreases B). non-spontaneous; decreases C). spontaneous; increases D). non-spontaneous; does not change E). non-spontaneous; increases
E). non-spontaneous; increases
Which is an example of matter? A). reactivity B). anxiety C). conductivity D). electrical current E). plastic
E). plastic
The scientific principle which is the basis for balancing chemical equations is A). the Law of Conservation of Energy. B). the Law of Definite Proportions. C). the Law of Conservation of Mass and Energy. D). Avogadro's Law. E). the Law of Conservation of Mass.
E). the Law of Conservation of Mass
When a reaction system is at equilibrium A). there is no more chemistry happening. B). the reaction rate in the reverse direction is at a minimum. C). the amounts of reactants and products are exactly equal. D). the reaction rate in the forward direction is at a maximum. E). the rates of the reaction in the forward and reverse directions are exactly equal.
E). the rates of the reaction in the forward and reverse directions are exactly equal.
All of the statements regarding redox reactions are true EXCEPT A). a reducing agent causes another substance to be reduced. B). alkali metals often behave as reducing agents because they readily lose electrons. C). metal ions are produced when pure metals are oxidized. D). halogens usually behave as oxidizing agents because they readily gain electrons. E). when a substance is oxidized its charge (or oxidation number) decreases.
E). when a substance is oxidized its charge (or oxidation number) decreases.
Bonds breaking are _________________.
Endothermic (from the Greek words endow (within) and therms (heat), meaning that the heat is put in)
Bond formation releases heat and is described as ____________.
Exothermic (from the Greek words exo (outside), meaning that heat goes out)
Consider the reaction: 2 CO (g) + O₂ (g) ↔ 2 CO₂ (g) The equilibrium expression for this reaction is:
[CO₂]²/[CO]²[O₂]
In the reaction shown, what is the mole ratio that would be used to determine the number of moles of oxygen needed to react with 3.2 moles of C₄H₁₀? 2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O
13 moles O₂/2 moles C₄H₁₀
In the reaction shown, what is the mole ratio that would be used to determine the number of moles of H₂ that would be produced when 3.5 moles of AlCl₃ are produced? 2 Al + 6 HCl → 2 AlCl₃ + 3 H₂
3 moles H₂/2 moles AlCl₃
The balanced equation for the reaction between aqueous ammonium sulfate and aqueous barium acetate is A). (NH₄)₂SO₄ (aq) + Ba(C₂H₃O₂)₂ (aq) → BaSO₄ (s) + 2 NH₄C₂H₃O₂ (aq). B). NH₄SO₄ (aq) + BaC₂H₃O₂ (aq) → BaSO₄ (s) + NH₄C₂H₃O₂ (aq). C). (NH₄)₂SO₃ (aq) + Ba(C₂H₃O₂)₂ (aq) → BaSO₃ (aq) + NH₄C₂H₃O₂ (aq). D). (NH₄)₂SO₄ (aq) + Ba(C₂H₃O₂)₂ (aq) → BaSO₄ (aq) + 2 NH₄C₂H₃O₂ (s). E). (NH₄)₂SO₄ (aq) + Ba(C₂H₃O₂)₂ (aq) → BaSO₄ (s) + NH₄C₂H₃O₂ (aq).
A). (NH₄)₂SO₄ (aq) + Ba(C₂H₃O₂)₂ (aq) → BaSO₄ (s) + 2 NH₄C₂H₃O₂ (aq).
The oxidation number of chlorine in the compound FeCl₃ is ________. A). -1 B). -3 C). +2 D). +3 E). -2
A). -1
As a pure element the oxidation number of zinc is ________, but in compounds such as ZnCO₃ its oxidation number is ________. A). 0; +2 B). 0; +1 C). 0; 0 D). +1; 0 E). none of the above
A). 0;+2
The molecular weight of PCl₃ is ________ amu. A). 137.33 B). 66.42 C). 136.00 D). 199.26 E). 139.00
A). 137.33
Consider the reaction shown: P₄ (s) + 10 Cl₂ (g) → 4 PCl₅ (s) + 452 kcal When 50.00 g of P₄ react, ________ kcal will be ________. A). 182.4; produced B). 452; consumed C). 182.4; consumed D). 729.7; produced E). 452; produced
A). 182.4; produced
How many molecules are present in 4.25 mol of CCl₄? A). 2.56 × 10²⁴ B). 9.26 × 10²⁵ C). 653.69 D). 153.81 E). 36.91
A). 2.56 × 10²⁴
Consider the reaction shown: 304.0 kcal + 4 PCl₃ (l) → P₄ (s) + 6 Cl₂ (g) When 50.00 g of PCl₃ react, ________ kcal will be ________. A). 27.67; consumed B). 110.7; consumed C). 304.0; produced D). 27.67; produced E). 304.0; consumed
A). 27.67; consumed
In the reaction shown, how many moles of HCl are needed to react with 2.4 moles of Al? 2 Al + 6 HCl → 2 AlCl₃ + 3 H₂ A). 7.2 B). 6.4 C). 0.8 D). 4.8 E). 1.3
A). 7.2
The formula weight of ammonium carbonate, (NH₄)₂CO₃, is ________ amu. A). 96.09 B). 82.10 C). 120.13 D). 64.11 E). 180.17
A). 96.09
Which of the following pairs will form ionic bonds with one another? A). Cs, Br B). Na, Ca C). S, Cl D). N, C
A). Cs, Br
Iron pyrite (fool's gold) is iron(II) sulfide. What is its formula? A). FeS B). Fe₂(SO₃)₃ C). FeSO₄ D). FeSO₃ E). Fe₂S₃
A). FeS
The HCO₃⁻¹ ion is called ________. A). hydrogen carbonate B). carbide C). carbonite D). hydrogen carbide E). carbonate
A). Hydrogen carbonate
Which of the following formulas represents a compound that is an acid? A). H₃PO₄ B). CaSO₄ C). NH₄Cl D). H₂O E). Mg(OH)₂
A). H₃PO₄
Which element is most likely to have chemical properties similar to those of bromine (atomic number 35)? A). I (atomic number 53) B). Kr (atomic number 36) C). Se (atomic number 34) D). Te (atomic number 52) E). S (atomic number 16)
A). I (atomic number 53)
The combination of ions is LEAST likely to produce a precipitate is A). Mg²⁺ and C₂H₃O₂⁻. B). Fe³⁺ and OH⁻. C). Ca²⁺ and PO₄³⁻. D). Ba²⁺ and SO₄²⁻. E). Pb⁺ and Cl⁻.
A). Mg²⁺ and C₂H₃O₂⁻.
Which statement concerning the mole concept is NOT true? A). One mole of any compound contains one mole of atoms. B). The molar mass of a metal is its atomic weight expressed in grams. C). One mole of sodium contains the same number of atoms as one mole of carbon. D). The mole concept makes a connection between the mass of a substance and the number of particles or units of that substance. E). One mole of water contains the same number of molecules as one mole of ammonia.
A). One mole of any compound contains one mole of atoms.
Covalent compounds form distinct molecules, and therefore may exist as gases, liquids, or solids at room temperature, depending on the characteristics of the compound. A). True B). False
A). True
A reaction which is unfavorable with respect to entropy, but favorable with respect to enthalpy A). could occur at low temperatures but not at higher temperatures. B). could not occur regardless of temperature. C). could occur at high temperatures but not at lower temperatures. D). could occur at any temperature. E). none of the above
A). could occur at low temperatures but not at higher temperatures.
Consider the reaction shown: C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O + 488 kcal We can say that this reaction is ________ and that the sign of ΔH is ________. A). exothermic; negative B). exothermic; neither positive nor negative C). endothermic; negative D). exothermic; positive E). endothermic; positive
A). exothermic; negative
2 Al₂O₃ (s) → 4 Al (s) + 3 O₂ (g) ΔG = +138 kcal Consider the contribution of entropy to the spontaneity of this reaction. As written, the reaction is ________, and the entropy of the system ________. A). non-spontaneous; increases B). spontaneous; decreases C). non-spontaneous; does not change D). spontaneous; increases E). non-spontaneous; decreases
A). non-spontaneous; increases
When a substance loses electrons it is ________; the substance itself is acting as a(an) ________ agent. A). oxidized; reducing B). reduced; oxidizing C). oxidized; oxidizing D). reduced; reducing E). dissolved; neutralizing
A). oxidized; reducing
The reaction 2 AgNO₃ (aq) + K₂SO₄(aq) → 2 KNO₃ (aq) + Ag₂SO₄ (s) is an example of a(an) ________ reaction. A). precipitation B). oxidation-reduction C). combustion D). acid-base E). none of the above
A). precipitation
Activation energy can best be described as A). the difference in energy between reactants and the maximum energy. B). the energy level of the reactants. C). the maximum energy level of the reaction. D). the difference in energy between reactants and products. E). the energy level of the products.
A). the difference in energy between reactants and the maximum energy.
The formula Ca(NO₃)₂ tells us that one formula unit of this compound is composed of ________ calcium atoms, ________ nitrogen atoms, and ________ oxygen atoms. A). one; two; five B). one; one; five C). one; two; six D). one; one; six E). two; two; six
C). one; two; six
In the reaction 2 C + O₂ → 2 CO, how many moles of carbon are needed to produce 66.0 g of carbon monoxide? A). 4.71 B). 2.36 C). 1.18 D). 28.3 E). 0.424
B). 2.36
The formula weight of Al₂(SO₄)₃ is ________ grams. A). 450.14 B). 342.14 C). 278.02 D). 214.14 E). 315.14
B). 342.14
Calculate the equilibrium constant for the reaction below if a tank was found to contain 0.106 M O₂, 0.00652 M SO₃ and 0.00129 M SO₂. 2 SO₃ (g) ↔ 2 SO₂ (g) + O₂ (g) A). 4.35 × 10⁻² B). 4.15 × 10⁻³ C) 6.78 × 10⁻² D). 1.34 × 10⁻²
B). 4.15 × 10⁻³
S + O₂ → SO₂ + 70.8 kcal Based on the reaction shown, which statement is TRUE? A). 70.8 kcal are consumed when 1 g of sulfur reacts. B). 70.8 kcal are produced when 32.1 g of sulfur reacts. C). 70.8 kcal are produced when 1 g of sulfur dioxide is produced. D). 70.8 kcal are produced when 1 g of sulfur reacts. E). 70.8 kcal are consumed when 32.1 g of sulfur reacts.
B). 70.8 kcal are produced when 32.1 g of sulfur reacts.
When a non-metal atom bonds with another non-metal atom, an ionic bond is formed. A). True B). False
B). False
Which factors would decrease the rate of a reaction? I. Lowering the temperature II. Increasing the concentration of reactants III. Adding a catalyst A). III only B). I only C). II only D). II and III E). I and III
B). I only
All of the reactions shown are oxidation-reduction reactions EXCEPT A). Zn(s) + 2 HCl(aq) → ZnCl₂ (aq) + H₂ (g). B). K₂SO₄ (aq) + BaCl₂ (aq) → BaSO₄ (s) + 2 KCl(aq). C). 2 Fe₂O₃ (s) → 4 Fe(s) + 3 O₂(g). D). N₂ (g) + O₂(g) → 2 NO(g). E). 2 NaI(aq) + Cl₂ (g) → 2 NaCl(aq) + I₂.
B). K₂SO₄ (aq) + BaCl₂ (aq) → BaSO₄ (s) + 2 KCl(aq).
2 SO₂ (g) + O₂ (g) ↔ 2 SO₃ (g) + heat K = 4.8 × 10²⁷ Which statement about this system is NOT true? A). The large value of K means that the reaction essentially goes to completion. B). Removing O₂ will cause an increase in the amount of SO₃. C). Adding SO₂ will cause an increase in the amount of SO₃. D). At equilibrium SO₃ is the predominant substance. E). Heating the system will cause breakdown of SO₃.
B). Removing O₂ will cause an increase in the amount of SO₃.
Which of the following elements is most likely to form an ion with a -2 charge? A). K B). S C). Si D). Mg E). Ti
B). S
Which of the following states of matter should have the lowest entropy value? A). a liquid B). a crystalline solid C). a gas D). Two of these have virtually the same entropy. E). all of the above
B). a crystalline solid
When a solution of iron(III) nitrate is mixed with a solution of sodium hydroxide, a rust colored precipitate forms. This precipitate is probably A). iron (III) nitrate. B). iron (III) hydroxide. C). sodium nitrate. D). sodium hydroxide. E). none of the above
B). iron (III) hydroxide.
Diatomic nitrogen is added to the equilibrium system: N₂ (g) + H₂ (g) ↔ 2 NH₃(g) + heat When a new equilibrium is established the concentration of H₂ will be ________ the amount at the original equilibrium, and the amount of NH₃ will be ________ the amount at the original equilibrium. A). greater than; greater than B). less than; greater than C). less than; less than D). greater than; less than E). Both changes will be impossible to determine.
B). less than; greater than
Diatomic nitrogen is added to the equilibrium system: N₂ (g) + H₂ (g) ↔ 2 NH₃(g) + heat When a new equilibrium is established the concentration of H₂ will be ________ the amount at the original equilibrium, and the amount of NH₃ will be ________ the amount at the original equilibrium. A). less than; less than B). less than; greater than C). greater than; greater than D). greater than; less than E). Both changes will be impossible to determine.
B). less than; greater than
The element chlorine is very reactive as a(an) ________ agent because it readily ________ electrons to form the chloride ion. A). oxidizing; loses B). oxidizing; gains C). reducing; gains D). reducing; loses E). none of the above
B). oxidizing; gains
The most common element by mass percent in the human body is A). sulfur. B). oxygen C). carbon. D). phosphorus. E). hydrogen.
B). oxygen
The scientific principle which explains the observation that the amount of heat transfer accompanying a change in one direction is numerically equal but opposite in sign to the amount of heat transfer in the opposite direction is A). the Law of Conservation of Mass and Energy. B). the Law of Conservation of Energy. C). Avogadro's Law. D). the Law of Conservation of Mass. E). the Law of Definite Proportions.
B). the Law of Conservation of Energy.
How many grams of fluorine are required to produce 20.0 grams of FeF₃ from the reaction shown? 2 Fe + 3F₂ → 2 FeF₃ A). 20.2 g B). 4.49 g C). 5.05 g D). 10.1 g E). 6.74 g
D). 10.1 g
The formula (NH₄)₃PO₄ indicates that one formula unit of this compound is composed of: A). one atom of nitrogen, twelve atoms of hydrogen, one atom of phosphorus, and four atoms of oxygen. B). three atoms of nitrogen, twelve atoms of hydrogen, one atom of phosphorus, and four atoms of oxygen. C). three atoms of nitrogen, twelve atoms of hydrogen, four atoms of phosphorus, and four atoms of oxygen. D). three atoms of nitrogen, seven atoms of hydrogen, one atom of phosphorus, and four atoms of oxygen. E). three atoms of nitrogen, twelve atoms of hydrogen, one atom of phosphorus, four atoms of oxygen, and six extra electrons.
B). three atoms of nitrogen, twelve atoms of hydrogen, one atom of phosphorus, and four atoms of oxygen.
In reactions, some bonds _________(energy in) so that new bonds can ________(energy out).
Break, Form
A student weighed 0.550 g of lithium chloride, LiCl, to use in a reaction. How many moles is this? A). 23.31 B). 42.39 C). 0.0130 D). 5.11 E). 77.08
C). 0.0130
Calculate the number of moles of aspirin, C₉H₈O₄, in a 4.0 gram tablet. A). 2.2 B). 4.6 × 10⁻³ C). 0.022 D). 2.2 × 10⁻⁴
C). 0.022
50.0 g of Cl₂ contains ________ mol Cl₂. A). 4.24 × 10²³ B). 1.41 C). 0.705 D). 1775 E). 50.0
C). 0.705
Consider the balanced equation shown and identify the statement that is NOT true. Na₂SO₄ (aq) + BaCl₂ (aq) → 2 NaCl (aq) + BaSO₄ (s) A).The products are barium sulfate and sodium chloride. B). Barium sulfate is produced in solid form. C). 2 NaCl (aq) could also be correctly written as Na2Cl₂ (aq). D). The coefficient of sodium sulfate is one. E). Barium chloride is dissolved in water.
C). 2 NaCl (aq) could also be correctly written as Na₂Cl₂ (aq).
How many moles of NaHCO₃ are present in a 2.00 g sample? A). 85.0 mol B). 2.00 mol C). 2.38 × 10⁻² mol D). 1.27 × 10⁻² mol E). 168 mol
C). 2.38 × 10⁻² mol
How many molecules are present in 4.25 mol of CCl₄? A). 36.91 B). 653.69 C). 2.56 × 10²⁴ D). 9.26 × 10²⁵ E). 153.81
C). 2.56 × 10²⁴
Which quantity contains Avogadros number of molecules? A). 8.8 g CO₂ B). 34 g of NH₃ C). 98 g of H₂SO₄ D). 9 g of H₂O
C). 98 g of H₂SO₄
Which is the correct equation for the reaction of magnesium with hydrochloric acid to produce hydrogen and magnesium chloride? A). Mg + 3 HCl → 3 H + MgCl₂ B). Mg + 2 HCl → 2 H + MgCl₂ C). Mg + 2 HCl → H₂ + MgCl₂ D). 2 Mg + 6 HCl → 3 H₂ + 2 MgCl₂ E). Mg + HCl → H + MgCl
C). Mg + 2 HCl → H₂ + MgCl₂
Which one of the compounds below is MOST likely to be ionic? A). H₂O B). CBr₄ C). SrBr₂ D). NO₂
C). SrBr₂
Elements in the Periodic Table are arranged according to A). number of neutrons. B). alphabetical order. C). atomic number. D). atomic weight. E). date of discovery.
C). atomic number.
The name of Cu²⁺ is ________ ion or ________ ion. A). copper(i); cupric B). copper(I); cuprous C). copper(II); cupric D). copper; cupric E). copper(II); cuprous
C). copper(II); cupric
A process which is unfavorable with respect to enthalpy, but favorable with respect to entropy A). could occur at low temperatures, but not at higher temperatures. B). could occur at any temperature. C). could occur at high temperatures, but not at lower temperatures. D). could not occur regardless of temperature. E). none of the above
C). could occur at high temperatures, but not at lower temperatures.
A reaction which is unfavorable with respect to entropy, but favorable with respect to enthalpy A). could occur at any temperature. B). could occur at high temperatures but not at lower temperatures. C). could occur at low temperatures but not at higher temperatures. D). could not occur regardless of temperature. E). none of the above
C). could occur at low temperatures but not at higher temperatures.
A rapid reaction is distinguished by A). being unaffected by catalysts. B). having a large heat of reaction. C). having a small value of activation energy. D). having a small heat of reaction. E). having a large value of activation energy.
C). having a small value of activation energy.
Which of the following is a pure substance? A). eggs B). bleach C). neon D). gasoline E). root beer
C). neon
Where is most of the mass of an atom concentrated? A). orbitals B). protons C). nucleus D). electrons E). neutrons
C). nucleus
How many grams of C will be consumed when 5.00 grams of Na₂SO₄ react according to the balanced reaction shown? Na₂SO₄ + 2 C → Na₂S + 2 CO₂ A). 0.038 g B). 1.69 g C). 0.211 g D). 0.844 g E). 17.1 g
D). 0.844 g
In the balanced reaction shown, the mole ratio of Fe₂S₃ to O₂ is Fe₂S₃ + 4 O₂ → 2 FeO + 3 SO₂ A). 1 to 2. B). 4 to 3. C). 5 to 5. D). 1 to 4. E). 4 to 1.
D). 1 to 4.
Determine the number of moles of water produced when one mole of NH₃ reacts according to the balanced reaction shown. 4 NH₃ + 5 O₂ → 4 NO + 6 H₂O A). 0.67 B). 1.33 C). 1.00 D). 1.50 E). 1.25
D). 1.50
Heat is the measure of the ___________ ___________ of the particles that make up the molecule.
Kinetic energy
When these attractive forces result in the formation of ionic or covalent bonds, the potential energy is often converted into_________.
Heat
A substance that has little remaining potential energy and, consequently, little tendency to undergo further change are ?
Stable
For a reaction to occur.......
reactant particles must collide, bonds have to break, and new bonds have to form
Free Energy (ΔG)
the combination of Enthalpy and Entropy
Law of Conservation of Energy
can be neither created nor destroyed in any physical or chemical change.
What is Kinetic Energy?
energy of motion. (Water falls over a dam and turns a turbine, The car rolls downhill, The spring uncoils and makes the hands on a clock move)
The __________ the bond dissociation energy, the more __________ the chemical bond.
greater, stable
The difference between the heat absorbed in breaking bonds and the heat released in forming bonds is the _________________________.
heat of reaction.
Bond Dissociation Energy
is the amount of energy that must be supplied to break a bond and separate the atoms in an isolated gaseous molecule.
What is Potential Energy?
it is stored energy. (The water in a reservoir behind a dam, An automobile poised to coast downhill, A coiled spring)
Entropy (ΔS)
meaning Chaos/Disorder
ergonic
meaning energy
Enthalpy (ΔH)
meaning heat of reaction
iso-
meaning same
thermic
means heat
The ______ __________ a molecule, the ______ ___________ it is.
more stable, less reactive
The colliding molecules........
must approach with the correct orientation so that the atoms that form new bonds can connect
If heat is released (exothermic) then the sign is ____________ to indicate energy is lost.
negative
The value of ΔG tells us......
only whether a reaction can occur; it says nothing about how fast the reaction will occur
If the heat is absorbed (endothermic) then the sign is ______________ to indicate energy is gained.
positive
The attractive forces between ions or atoms are a form of ______________________.
potential energy